There is a known technology in which a burner is provided in an exhaust passage of an internal combustion engine upstream of an exhaust gas purification apparatus including an exhaust gas purification catalyst and/or a particulate filter in order to raise the temperature of the exhaust gas purification apparatus (see, for example, Patent Documents 1 and 2). Such a burner has a burner combustion chamber, and fuel supplied into the burner combustion chamber is burned to raise the temperature of the exhaust gas flowing into the exhaust gas purification catalyst.
Patent Document 3 discloses a burner that can take in a portion of the exhaust gas diverted from the main stream of the exhaust gas and burn fuel. Moreover, Patent Document 3 describes the technique of arranging the burner in such a way that the emitted flame does not interfere directly with the main stream of the exhaust gas in order to achieve stable burning. Furthermore, Patent Document 3 describes the result of measurement of the stability of the flame in the case where the flame of the burner does not interfere directly with the mainstream of the exhaust gas and in the case where the flame interferes with the main stream of the exhaust gas. In the document, the measurement results are given for the idle state, high rotation speed operation state, and normal operation state respectively.
Patent Document 4 discloses a technology pertaining to a catalyst temperature raising apparatus having a pre-mixing space in which air and fuel are mixed to form air-fuel mixture and an ignition plug that ignites the air-fuel mixture formed in the pre-mixing space, in which a combustion catalyst is provided between the region in which the pre-mixing space and the ignition plug are disposed and the exhaust gas purification catalyst. Furthermore, Patent Document 4 describes a technique in which when the temperature of the exhaust gas purification catalyst does not need to be raised much, air and fuel are supplied without igniting the air-fuel mixture in the pre-mixing space.